Farnesene-based polymers and liquid optically clear adhesive compositions incorporating the same

ABSTRACT

A low viscosity polymer having a linear or branched backbone derived from farnesene monomers and at least one terminal-end functionalized with a hydroxyl group. This polymer may be further hydrogenated to reduce unsaturation and acrylated, such that it may be incorporated into a LOCA composition. The LOCA composition may be used in a laminated screen assembly, such as a touch screen, for electronic devices by adhering the LOCA composition between an optically transparent layer, such as a cover glass, and a display. The cured LOCA composition has a refractive index similar to the optically transparent layer. A method of making the low viscosity polymer for the LOCA composition includes anionically polymerizing farnesene monomers, quenching a living end of the polymer to provide the hydroxyl-terminated polymer; hydrogenating the hydroxyl-terminated polymer; and reacting the at least partially saturated hydroxyl-terminated polymer with at least one reagent to provide an acrylate terminated hydrogenated polymer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/753,449, filed Jun. 29, 2015, which is incorporated herein byreference in its entirety for all purposes.

FIELD OF THE INVENTION

The invention relates to liquid optically clear adhesive (LOCA)compositions and laminated assemblies incorporating the adhesive. Morespecifically, the invention relates to LOCA compositions comprising alow viscosity polymer derived from farnesene.

BACKGROUND

A display is an indispensable interface that allows human-machinecommunication for electronic products, such as mobile phones, personaldigital assistants, tablets, and notebooks. Recently, touch panels havebeen integrated with displays in various electronic products; users canconduct various operations through touching the panel in a moreconvenient fashion. How to provide products that are lighter and thinnerand have better visual effects has always been one of the mainobjectives behind the developments within the electronics industry, andthe same is true for the new generation of products that incorporatelaminated touch panel/display components.

Optical bonding is bonding of two or more optical components togetherusing a clear optical refractive index-matched adhesive. In its simplestform, optical bonding eliminates the air gap between the a transparentcover, such as a cover glass, and the underlying display, such as anLCD, for example. Removing the air gap eliminates two reflectivesurfaces and reduces specular reflection. To prevent affecting visualeffects, such adhesives should exhibit proper optical properties such asproper light transmittance and refractive index. When light travelsthrough different mediums, reflection occurs due to the difference inrefractive indexes, thereby affecting light's extraction efficiency.Optical devices, such as thin film and glass, usually have a relativelyhigh refractive index. For example, the refractive index of glass isabout 1.52. A disadvantage to many clear adhesives is that theirrefractive index is not sufficiently close to the glass substrates towhich they may be applied. A common optically-transparent adhesive, suchas acrylate adhesive, has a refractive index of about 1.4 to 1.45, whichcannot meet current industry standards.

Fully hydrogenated C4 diol resins enable the formulation of opticallyclear adhesives which are generally used today in touchscreenapplications, such as current generation smart phones. Optically clearadhesives allow for touch screens based on capacitive technology toeliminate a traditional multi-layer construction, thereby allowingmanufacturers to create thinner, lighter devices. Polybutadiene diolsare well-defined, pure materials that when selectively hydrogenated,produce very clear diols which meet the tight refractive index andclarity specifications required for these applications.Polybutadiene-based adhesives also demonstrate excellent moistureresistance and flexibility over a wide temperature range, effectivelyprotecting the sensitive optics and other electronic components of thedevice. Polybutadiene-based adhesives however have high viscositiesmaking the handling and application of this material difficult unlessthe adhesives are diluted, and dilution may negatively impact therefractive index of the adhesive. Thus, there is a need for new andimproved low viscosity optically-transparent adhesives with a highrefractive index.

SUMMARY OF THE INVENTION

It is a first aspect of the present invention to provide a polymercomprising a linear or branched backbone derived from monomerscomprising farnesene having at least one terminal-end functionalizedwith a hydroxyl group. This polymer may serve as an intermediate thatmay be acrylated.

Another aspect of the present invention is to provide a liquid opticallyclear adhesive composition comprising a polymer derived from monomerscomprising farnesene and having at least one terminal end functionalizedwith an acrylate group and a degree of unsaturation less than or equalto 50%.

It is yet another aspect of the present invention to provide a liquidoptically clear adhesive composition comprising a polymer having astructure according to Formula (I),

wherein [Polymer] is a linear or branched polymer backbone derived frommonomers comprising farnesene, R1 is in alkyl group or R2, and R2 has astructure according to Formula (II) or Formula (III),

wherein Y and Z are independently selected from the group consisting oflinear, cyclic, aliphatic, aromatic, substituted, and non-substitutedhydrocarbon groups, andX is independently selected from the group consisting of hydrogen and analkyl group.

In yet another aspect of the present invention, a method of preparing aliquid optically clear adhesive composition is provided. The methodcomprising:

-   -   anionically polymerizing monomers to provide a polymer having at        least one living end, the monomers comprising farnesene;    -   quenching the at least one living end to provide a        hydroxyl-terminated polymer;    -   hydrogenating the hydroxyl-terminated polymer to provide an at        least partially saturated hydroxyl-terminated polymer; and    -   reacting the at least partially saturated hydroxyl-terminated        polymer with at least one reagent to provide an acrylate        terminated hydrogenated polymer.

Yet another aspect of the present invention is to provide a laminatedscreen assembly comprising a transparent layer adhered to a display anda cured adhesive between the transparent layer and the display, whereinthe adhesive is a liquid optically clear adhesive composition accordingto the present invention.

These and other aspects of the various embodiments the present inventionwill be understood from the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments of the present invention include farnesene-basedintermediate polymers, the hydrogenated and acrylated products of theseintermediates, and the LOCA compositions and laminated assembliescomprising the acrylated-polymers. The polymers may be obtained bypolymerizing a monomer feed that primarily includes farnesene. Theadhesive compositions incorporating the farnesene-based polymers mayexhibit a refractive index when cured similar to hydrogenatedpolybutadienes, but have a lower viscosity compared to hydrogenatedpolybutadienes. Therefore, the polymers have improved rheologicalproperties and may be handled favorably in adhesive formulations withoutsignificant dilution with other photosensitive components that may afterthe refractive index of the cured adhesive.

It has been found that polymerizing farnesene according to the presentinvention results in low viscosity polymers. Any methods known by thosehaving skill in the art may be used to polymerize the farnesene monomersand include, but are not limited to, anionic or free radicalpolymerization. Anionic polymerization is particularly preferred becauseanionic polymerization allows greater control over the final molecularweight of the polymer. The living terminal end of the polymer may alsobe easily quenched using an epoxide followed by contact with a proticsource providing a monol, dial, or polyol. The resulting hydroxyl groupson the terminal ends of the polymeric farnesene-based monol, dial, orpolyol may be reacted further to provide acrylate groups, for example,such that the polymer may be useful as a curable LOCA composition. Thelow viscosity farnesene-based polymers prepared according to the presentinvention may be derived by polymerizing farnesene monomer along or withat least one other monomer. It is preferred that the polymers madeaccording to various embodiments of the present invention are derivedfrom a monomer feed that is primarily composed of farnesene.

According to certain embodiments of the invention, a farnesene-basedpolymer is provided having a structure according to Formula (I),

wherein [Polymer] is a linear or branched polymer backbone derived frommonomers comprising farnesene, R1 is in alkyl group or R2, and R2 has astructure according to Formula (II) or Formula (III),

wherein Y and Z are independently selected from the group consisting oflinear, cyclic, aliphatic, aromatic, substituted, and non-substitutedhydrocarbon groups, and X is independently selected from the groupconsisting of hydrogen and an alkyl group.

Farnesene exists in isomer forms, such as α-farnesene((E,E)-3,7,11-trimethyl 1,3,6,10-dodecatetraene) and β-farnesene(7,11-dimethyl-3-methylene-1,6,10-dodecatriene). As used in thespecification and in the claims, “farnesene” means (E)-β-farnesenehaving the following structure:

as well (E)-β-farnesene in which one or more hydrogen atoms have beenreplaced by another atom or group of atoms (i.e. substituted).

The farnesene monomer used to produce various embodiments of the polymeraccording to the present invention may be prepared by chemical synthesisfrom petroleum resources, extracted from insects, such as Aphididae, orplants. Therefore, an advantage of the present invention is that thepolymer may be derived from a monomer obtained via a renewable resource.It is preferably prepared by culturing a microorganism using a carbonsource derived from a saccharide. The farnesene resin according to thepresent invention may be efficiently prepared from farnesene monomerobtained via these sources.

The saccharide used may be any of monosaccharides, disaccharides, andpolysaccharides, or may be a combination thereof. Examples ofmonosaccharides include glucose, galactose, mannose, fructose, andribose. Examples of disaccharides include sucrose, lactose, maltose,trehalose, and cellobiose. Examples of polysaccharides include starch,glycogen, and cellulose.

The cultured microorganism that consumes the carbon source may be anymicroorganism capable of producing farnesene through culturing. Examplesthereof include eukaryotes, bacteria, and archaebacteria. Examples ofeukaryotes include yeast and plants. The microorganism may be atransformant obtained by introducing a foreign gene into a hostmicroorganism. The foreign gene is not particularly limited, and it ispreferably a foreign gene involved in the production of farnesenebecause it can improve the efficiency of producing farnesene.

In the case of recovering farnesene from the cultured microorganism, themicroorganism may be collected by centrifugation and disrupted, and thenfarnesene can be extracted from the disrupted solution with a solvent.Such solvent extraction may appropriately be combined with any knownpurification process such as distillation.

In yet another embodiment of the present invention, a method of making alinear or branched farnesene-based polymer useful in a LOCA compositionis provided comprising anionically polymerizing monomers to provide apolymer having at least one living end, the monomers comprisingfarnesene; quenching the at least one living end to provide ahydroxyl-terminated polymer; hydrogenating the hydroxyl-terminatedpolymer to provide an at least partially saturated hydroxyl-terminatedpolymer; and reacting the at least partially saturatedhydroxyl-terminated polymer with at least one reagent to provide anacrylate terminated hydrogenated polymer. “Acrylate-terminated” as usedherein means both an acrylate or methacrylate functional group on theterminal end of the polymer.

The farnesene-based polymers described herein may be prepared by acontinuous solution polymerization process wherein an initiator,monomers, and a suitable solvent are continuously added to a reactorvessel to form the desired homopolymer or co-polymer. Alternatively, thefarnesene-based polymers may be prepared by a batch process in which allof the initiator, monomers, and solvent are combined in the reactortogether substantially simultaneously. Alternatively, thefarnesene-based polymers may be prepared by a semi-batch process inwhich all of the initiator and solvent are combined in the reactortogether before a monomer feed is continuously metered into the reactor.

Preferred initiators for providing a polymer with living terminal chainends include, but are not limited to organic salts of alkali metals. Thepolymerization reaction temperature of the mixture in the reactor vesselmay be maintained at a temperature of about −80 to 80° C.

As understood by those having skill in the art, anionic polymerizationmay continue, as long as monomer is fed to the reaction. Thefarnesene-based polymers used in LOCA compositions according to thepresent invention may be polymerized from farnesene and one or morecomonomers. Examples of comonomers include, but are not limited to,diener, such as butadiene, isoprene, and myrcene, in which butadiene andisoprene are preferred. In one embodiment of the present invention, amethod of manufacturing a LOCA composition may comprise polymerizing amonomer feed, wherein the monomer feed comprises farnesene monomer and acomonomer in which the comonomer content of the monomer feed is ≤75 mol.%, more preferably ≤50 mol. %, and most preferably ≤25 mol. %, based onthe total moles of the monomer in the monomer feed.

The low viscosity farnesene-based hams-polymers or co-polymers accordingto embodiments of the present invention may have a number averagemolecular weight less than or equal to 100,000 g/mol, preferably lessthan or equal to 25,000 g/mol, as measured through a gel permeationchromatograph and converted using polystyrene calibration. Thefarnesene-based homo-polymers or co-polymers prior to curing may have aviscosity less than or equal to 100,000 cP, more preferably less than50,000 cP, and most preferably less than or equal to 25,000 cP, whereinviscosity is measured for the LOCA composition at 60° C.

The quenching step to end polymerization is preferably accomplished byreacting the a living terminal end(s) of the living polymer with analkylene oxide, such as propylene oxide, and a protic source, such as anacid, resulting in a monol, diol, or polyol, i.e. a hydroxyl group onthe terminal end(s) of the polymer.

Following polymerization, the hydroxyl-terminated polymer is preferablyhydrogenated to decrease the degree of unsaturation of the polymer to atmost 50%, more preferably at most 10%. Degree of unsaturation isdetermined by analytical methods known in the art, such as iodine value.

Acrylate functionalization on the terminal ends of the farnesene-basedpolymers according to the present invention may be accomplished byreacting the hydroxyl-terminated polymer with at least one reagent. Forexample, acrylate functionalization may be accomplished by either directesterification of the hydroxyl groups with an acrylate derivate(s) orthrough a urethane group by reacting an isocyanate-containing compound,preferably a diisocyanate, with an acrylate and hydroxylgroup-containing compound as well as the hydroxyl-terminated polymer.The isocyanate may be selected from the group consisting of isophoronediisocyanate, methylene dicyclohexylisocyanate, 1,6-hexamethylenediisocyanate, and the like. The acrylate and hydroxyl group-containingcompound may be selected from the group consisting of 2-hydroxyethylacrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl acrylate, andpolyethylene glycol (meth)acrylate. Useful reagents for directesterification preferably have acrylate functionality, such as acrylicacid, acrylic anhydride, acrylic chloride, or alkyl acrylates.

As discussed above, certain embodiments of the present invention includeLOCA compositions comprising a polyfarnesene-based polymer, A LOCAcomposition made according to the present invention may have reducedlevels of reactive diluent and/or plasticizers. Because thefarnesene-based polymers of the present invention exhibit low viscosity,less diluent and/or plasticizers are needed to achieve a targetviscosity for the LOCA compositions in which they are incorporated byreplacing the higher viscosity polybutadiene-based polymers. Thus,certain embodiments of the present invention provide low viscosity LOCAcompositions that may comprise a mixture of hydrogenated acrylatedfarnesene-based polymers and hydrogenated acrylated polybutadiene. LOCAcompositions according to the present invention may include 50-90 wt. %,more preferably 60-80 wt. %, and most preferably 65-75 wt. % of thefarnesene-based polymer, based on the total weight of the LOCAcomposition.

LOCA compositions according to the present invention may include one ormore reactive diluents. The reactive diluent may include monomersselected from the group consisting of isobornyl acrylate, isobornyl(meth)acrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfurylmethacrylate, alkoxylated tetrahydrofurfuryl acrylate, alkoxylatedmethacrylate, tetrahydrofurfuryl methacrylate and mixtures thereof.Specific examples of reactive diluent include2-(tricyclo[5.2.1.0(2,6)]dec-3(or 8)-enyloxy)ethyl methacrylate and2-hydroxyethyl methacrylate. LOCA compositions according to the presentinvention may include 25-55 wt. %, more preferably 30-50 wt. %, and mostpreferably 35-45 wt. % of reactive diluent, based on the total weight ofthe LOCA composition

The LOCA compositions according to the present invention may alsoinclude additional components including, but not limited to, fillers,plasticizers, and tackifying resins. It is preferred that the variouscomponents of the LOCA compositions of the present invention areselected, such that they are compatible with each other and do not phaseseparate and negatively affect the refractive index of the material.

For example, a plasticizer that increases the softness and flexibilityof the cured material may be incorporated in various embodiments of thepresent invention. Plasticizers are well known and typically do notparticipate in polymerization of (meth)acrylate groups. One or moreplasticizers may be selected from the group consisting of vegetable oil,mineral oil, soybean oil, terpine resins, unsubstituted orcarboxy-substituted polyisoprene, polybutadiene, or polybutylene resins,xylene polymer, hydroxyl-terminated polybutadiene or polyolefins, andhydrogenated diene or polybutadiene resins, such as butadiene resins. Ifpresent, LOCA compositions according to the present invention mayinclude 20-50 wt. %, more preferably 25-45 wt. %, and most preferably30-40 wt. % of plasticizer, based on the total weight of the LOCAcomposition.

Any common tackifiers typically used in a LOCA composition that areknown by those having skill in the art may be used in the LOCAcompositions according to the present invention. An example of atackifier is hydrogenated terpene resin, such as hydrogenatedcyclohexene, 1-methyl-4-(1-methylenthenyl)-homopolymer sold under thetrade name Clearon P85 by Yasuhara Chemical Co, Ltd. If present, LOCAcompositions according to the present invention may include 20-50 wt. %,more preferably 25-45 wt. %, and most preferably 30-40 wt. % oftackifier, based on the total weight of the LOCA composition.

Other optional components of the LOCA compositions according to thepresent invention include, but are not limited to, silicone-basedadhesives for additional curable materials, metal oxide particles formodifying the refractive index of the cured material, and rheologymodifiers. Photoinitiators may be used in the LOCA compositions whencuring with UV radiation. Free radical initiators include organicperoxides, azo compounds, and the like. One example of a UV curing agentis Irgacure 184D sold by BASF. If present, it is preferred that one ormore photoinitiators are present in an amount less than or equal to 10wt. %, more preferably less than or equal to 5 wt. %, and mostpreferably less than or equal to 3 wt. %, based on the total weight ofthe LOCA composition. The liquid compositions and adhesive layers canoptionally include one or more additives such as antioxidants,stabilizers, fire retardants, viscosity modifying agents, antifoamingagents, antistatic agents and wetting agents.

In yet another embodiment of the present invention, a laminated screenassembly is provided comprising an optically transparent layer adheredto a display, such as an LCD, an organic electroluminescence panel,electrophoretic display, or plasma display, and a cured adhesive betweenthe transparent layer and the display, wherein the adhesive is a LOCAcomposition comprising a farnesene-based polymer. The laminated screenassembly may further comprise a touch panel sensor layer between thetransparent layer and the display, wherein the cured adhesive is adheredto the touch panel sensor layer and at least one of the transparentlayer and the display. In other embodiments, the touch panel sensorlayer may be disposed between two optically transparent layers. Thetouch panel sensor layer may comprise indium tin oxide. The laminatedscreen assemblies according to various embodiments of the presentinvention may be incorporated in a variety of devices including, but notlimited to, a handheld device such as a phone, a television, a computermonitor, an automotive interior display, a projector, or a sign. Theoptical device may comprise a backlight.

LOCA compositions according to the present invention may be used to fillgaps between optical components or substrates of a laminated screenassembly in electronic products. A gap between component layers of thelaminate may be filled by pouring or injecting a curable compositioninto the gap followed by curing the composition to bond the componentstogether. Assemblies having a filled gap can exhibit improvedshock-resistance compared to the same assemblies having an air gap.

The optically transparent layer used in the laminated screen assemblymay comprise any transparent material known to those having skill in theart, such as glass or a polymer, for example. Useful glasses includeborosilicate, soda lime, and other glasses suitable for use in displayapplications as protective covers. Useful polymers include polyesterfilms such as polyethylene terephthalate, polycarbonate films or plates,acrylic films such as polymethylmethacrylate films, and cyclo-olefinpolymer. The transparent material may be in the form of a cover lens,for example.

As explained above, the LOCA compositions incorporated in the laminatedscreen assemblies according to various embodiments of the inventionpreferably has a refractive index that matches or closely matches thatof the display and/or optically transparent layer. For example, thecured LOCA composition may have a refractive index greater than or equalto 1.4, more preferably greater than or equal to 1.45, and mostpreferably greater than or equal to 1.5. It is most preferably preferredthat the cured LOCA composition has a refractive index within 10% of therefractive index of the optically transparent layer, more preferablywithin 5%.

LOCA compositions according to the present invention may facilitateeasier manufacture of assemblies having a large size or area. Forexample, panels and substrates having a large area will also have largegaps requiring a large volume of low viscosity adhesive to adequatelyfill the entire gap. Highly viscous compositions may be difficult toapply and may take longer to completely fill such large volumes, thusrequiring diluted compositions to provide a less viscous and more easilyapplied composition. However, diluted compositions, as explained above,may result in adhesive compositions having less than optimal refractiveindices when cured, and a poorly mixed large volume of adhesive may alsoresult in non-uniform optical characteristics over the area of the panelassembly. LOCA compositions according to the present invention avoidthese disadvantages by providing compositions having a high refractiveindex and low viscosities that do not generally require a diluent forapplication. For ease of application of the adhesive and improvedmanufacturing of the laminated screen assemblies, it is also preferredthat the LOCA compositions prior to curing have a viscosity less than orequal to 10,000 cP, most preferably less than or equal to 5,000 cP,wherein viscosity is measured for the LOCA composition at 25° C.

The LOCA compositions according to the present invention may be appliedby any method known to those of skill in the art. The low viscosity ofthe composition allow them to be easily applied by spray or coatingmethods, for example. Methods used to assemble the laminated screenassemblies according to the present invention are known by those havingskill in the art, for example, the methods described in U.S. Pat. No.6,361,389 and U.S. Pat. No. 5,867,241, which are incorporated herein byreference in their entireties. The LOCA composition may be cured duringapplication to one of the layers of the assembly or after assembly ofthe laminated panel assemblies by UV-radiation and/or heat. Electronbeam radiation may also be used.

EXAMPLE

An embodiment of the present invention is furthers described using thefollowing non-limiting example.

Step A—Farnesene-Based Diol Synthesis

In a semi-batch process, a difunctional organolithium initiator in apolar solvent was transferred to a reactor, and sufficient farnesenemonomer to achieve an approximate target molecular weight of 2000 g/molwas continuously added. The polymerization reaction was performed at25-40° C. and terminated with an excess of propylene oxide followed byneutralization with a weak acid and the addition of BHT as anantioxidant to provide a poly-farnesene diol. The final solution waswashed with water to reduce/eliminate alkalinity. The organic phase wasseparated from water phase and then solvent was removed from theseparated organic phase by steam stripping under nitrogen atmosphere.

Step B—Hydrogenation

319 g of the poly-farnesene dual, 7.2 g of Ni catalyst and 336 g ofheptane as a solvent were transferred to a pressure reactor, followed bypurging with hydrogen three times. The reaction temperature was set to100-130° under hydrogen pressure. Before the temperature reached theboiling point of the solvent, the reaction mixture was purged withnitrogen three times and hydrogen was continuously fed to the reaction.The reaction temperature was controlled by stirring speed and hydrogenpressure. In order to monitor the reaction, aliquot samples wereperiodically taken and analyzed using FTIR after drying the solvent. Theunsaturated peak was measured of each sample. This procedure wasrepeated until the unsaturated peaks disappeared completely. Thereaction mixture was then cooled down to room temperature, catalyst wasremoved by filtration, and the final solution was stripped under vacuum.

Step C—Acrylation

Urethane acrylates were first prepared by reacting isophoronediisocyanate (IPDI) with 2-hydroxyethyl acrylate (HEA) to make acrylatedisocyanate, 25 g of IPDI, 0.25 g of Irgonox 1010, and 0.25 g ofdibutyltin dilaurate (DBTDL) were transferred to a resin kettle equippedwith a mechanical stirrer, thermocouple, dropping funnel, and airspurge. 11.9 g of 2-hydroxyethyl acrylate (HEA) was continuously addedto the reaction mixture at room temperature, and the temperature reached40° C. after complete addition.

The acrylated isocyanate was then reacted with a sample of thehydrogenated polyfarnesene diol from Step B or with a comparative sampleof hydrogenated polybutadiene diol (Krasol HLBH-P2000 manufactured byTotal Cray Valley of Exton, Pa.) according to the reaction shown below.

0.17 g of Irgonox 1010 and 0.25 g of DBTDL was added to the reactor, and125 g of dial was gradually added and increased the temperature to 70°C. An aliquot of reaction mixture was sampled to measure the NCO valueafter 1 hour. Additional diol was added until the NCO value was below 1mg KOH/g. The viscosity and refractive index (RI) was measured of theacrylated material, and the results are provided below in Table 1.Viscosity was measured using a Brookfield viscometer DV-II+Pro and asize 31 spindle. The rpm setting for HLBH-P2000 was 0.3 and 6.0 for thehydrogenated poly-farnesene.

TABLE 1 Diol Viscosity @60° C. (cps) RI HLBH-P2000 54,400 1.482Hydrogenated 2,055 1.476 Poly-FarneseneAs demonstrated in the results provided in Table 1, the acrylated andhydrogenated polyfarnesene made according to an embodiment of thepresent invention exhibited a refractive index similar to that of thepolybutadiene-based material, but had a significantly lower viscosity.

While preferred embodiments of the invention have been shown anddescribed herein, it will be understood that such embodiments areprovided by way of example only. Numerous variations, changes, andsubstitutions will occur to those skilled in the art without departingfrom the spirit of the invention. Accordingly, it is intended that theappended claims cover all such variations as fall within the spirit andscope of the invention.

We claim:
 1. A method of preparing a liquid optically clear adhesivecomposition comprising: anionically polymerizing monomers to provide apolymer having at least one living end, the monomers comprisingfarnesene; quenching the at least one living end to provide ahydroxyl-terminated polymer; hydrogenating the hydroxyl-terminatedpolymer to provide an at least partially saturated hydroxyl-terminatedpolymer; and reacting the at least partially saturatedhydroxyl-terminated polymer with one or more reagents that form aurethane group to provide an acrylate terminated hydrogenated polymerhaving a urethane group.
 2. The method of claim 1, wherein the monomersfurther comprise one or more dienes.
 3. The method of claim 2, whereinthe dienes are selected from the group consisting of butadiene,isoprene, and myrcene.
 4. The method of claim 1, wherein the polymer hastwo living ends that are quenched to provide a diol.
 5. The method ofclaim 1, wherein the at least partially saturated hydroxyl-terminatedpolymer has a degree of unsaturation less than or equal to 50%.
 6. Themethod of claim 1, wherein the at least partially saturatedhydroxyl-terminated polymer has a degree of unsaturation less than orequal to 10%.
 7. The method of claim 1, wherein the one or more reagentscomprise isophorone diisocyanate and 2-hydroxyethyl acrylate.
 8. Themethod of claim 1, wherein the one or more reagents comprise adiisocyanate and an acrylate and hydroxyl group-containing compound. 9.A method of preparing a liquid optically clear adhesive compositioncomprising: anionically polymerizing monomers to provide a polymerhaving at least one living end, the monomers comprising farnesene;quenching the at least one living end by reacting the at least oneliving end with an alkylene oxide and a protic source to provide ahydroxyl-terminated polymer; hydrogenating the hydroxyl-terminatedpolymer to provide an at least partially saturated hydroxyl-terminatedpolymer; and reacting the at least partially saturatedhydroxyl-terminated polymer with an acrylic anhydride or an acrylicchloride to form an acrylate terminated hydrogenated polymer containingan ester group.